Suave, sophisticated Captain "Bulldog" Drummond (John Howard) is back in this sixth installment of the popular series based on H.C. McNeile's detective stories.

Drummond is all set to marry his sweetheart, Phyllis Clavering (Heather Angel), when the eccentric Professor Downie (Forrester Harvey) suddenly arrives, informing the Captain that there is a buried treasure hidden somewhere on his estate…and that he has the secret cipher that will lead them to it. However, after deciphering the code, the professor is murdered!

More like a horror film than a typical Bulldog adventure, Drummond explores the manor's mysterious, unknown passageways…uncovering a gothic torture chamber in his quest to discover both the treasure and the identity of the professor's killer.

This film includes a short retrospective of the prior Bulldog movies in the form of an inventive dream sequence triggered by the Captain's pre-nuptial jitters.